AL 3 (BH 261)

RA:

18:14:06.6

Dec:

-28:38:06

Distance from Sun:

21.2 kly

Distance from Galactic Center:

5.5 kly

Apparent Diameter:

1.3 arc min

Brightness:

11.00 mag vis

Radial Velocity:

+/- km/s

Diameter:

ly

Abs. Mag:

-4.19 Mag vis

AL3 (Andrews-Lindsay 3) was discovered in 1967 by Andrews and Lindsay (1967); it was later cataloged by Van den Bergh and Hagen (1975) as BH 261 or vdB-Ha 261, and as ESO 456-SC78 by Lauberts et.al. (1982).

While all these authors listed it as a faint open cluster candidate, investigations by Ortholani et.al. (2006) have revealed its nature as a globular cluster by means of spectrophotometric observations, i.e. photometry in B, V, and I band of the spectrum, and Color-Magnitude Diagram. That diagram resembles that of globular cluster M5 and exhibits a prominent blue extended Horizontal Branch. These observations were performed at ESO (La Silla)

References:

• A.D. Andrews and E.M. Lindsay, 1967. Irish Astronomical Journal, Vol. 8, pp. 126-127. [ADS: 1967IrAJ....8..126A]
• Lauberts et.al., 1982. ESO/Uppsala Survey of ESO(B) Atlas, ESO, Garching. [ADS: 1982euse.book.....L]
• S. Ortolani, E. Bica and B. Barbuy, 2006. AL 3 (BH 261): a new globular cluster in the Galaxy. To appear in: Astrophysical Journal Letters. [Preprint: astro-ph/0606718]
• Sidney van den Bergh and Gretchen L. Hagen, 1975. Uniform survey of clusters in the Southern Milky Way. Astronomical Journal, Vol. 80, No. 1, p. 11-16 (Jan 1975) [ADS: 1975AJ.....80...11V]